Effect of residual stress on the photoluminescence spectra of EuCl2 powder

Photoluminescence spectra of EuCl2 powder compacts with various compaction pressures have been measured under ambient conditions and they are found significantly redshifted compared with those of the original powder by as much as 11 nm at the compaction pressure of ∼1.3 GPa. Observed redshifts appear to be caused by residual stress in the compacts in view of X-ray diffraction results. The luminescence peak position of the compact can be easily tuned between 408 and 419 nm by simply changing the compaction pressure applied to EuCl2 powder. The residual stress can be relieved by thermally annealing the compacts and the luminescence peak position returns to the original position.